This invention relates to a method of manufacturing a hollow metal ball bat and to the product resulting from the use of the method. More particularly, it relates to a new and advantageous technique for attaching an end knob to the handle portion of a hollow metal baseball bat.
The familiar form of a baseball bat has a relatively large body portion at one end and a relatively small handle portion at the other end. The handle portion is terminated by a knob or ring-like enlargement which serves to prevent the handle from flying out of the batter's hands as the bat is swung. When baseball bats are turned from wood stock, the end knob is simply formed as an integral enlargement at the bottom of the handle portion. In the case of bats formed of hollow metal, technical and economic limitations of the metal forming process generally dictate that the smoothly tapered bat body and integral handle portion be formed as one unit, while the end knob is formed separately and subsequently affixed to the end of the handle.
In one prior art method of making a metal ball bat, the end knob is formed with a plug or extension adapted to be inserted into the hollow end of the bat handle, which is then crimped to hold the knob in place. This method, disclosed in U.S. Pat. No. 3,735,473 to Wilson, requires elaborate and expensive electrical equipment to generate a pulsed magnetic field which deforms or crimps the metal bat handle.
Another prior art metal bat utilizes a metal end knob formed with an interior cavity adapted to fit over the end of the bat handle portion where it is retained by a circumferential weld. The welding process requires expensive and elaborate electrical apparatus and produces a weld bead at the junction of the knob and handle which may be considered unattractive in sports equipment marketed to the general public.